Implantable Nuclear Prosthesis

ABSTRACT

A nuclear disc implant includes an inner fillable enclosure and an outer fillable enclosure. After insertion into a enucleated disc cavity, the inner enclosure is filled with a fluid and the outer fillable enclosure is filled with a curable material. The curable material is allowed to cure and the fluid is removed from the inner enclosure to leave an inner enclosure surrounded by an cured outer enclosure. A reinforcing band may be provided around the nuclear disc implant. An inflation tool to fill the nuclear disc implant is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/212,950 filed Sep. 1, 2015, the entire contents of which isspecifically incorporated herein by reference without disclaimer.

BACKGROUND 1. Field of the Invention

This application relates generally to methods and devices for replacingan intervertebral disc. More specifically, the application relates to animplantable disc replacement which may be implanted using minimallyinvasive surgical techniques or percutaneously, and methods formanufacturing such a disc replacement/prosthesis.

2. Description of Related Art

A common medical issue is back pain due to spinal disc injuries causedby trauma, the aging process or other disorders. One method of treatmentthat has been proposed is to remove the existing nucleus pulposus andreplace it with a nuclear prosthesis formed in situ using open surgeryor minimally invasive surgical techniques. One proposed method comprisesthe steps of (i) providing a mold, such as a balloon, to contain aflowable curable material that can cure in situ within the disc space,(ii) providing a conduit to connect the mold cavity to a source offlowable curable material, (iii) delivering the flowable curablematerial into the mold to fill the cavity, and (iv) permitting thecurable material to cure.

The existing techniques for forming a nuclear prosthesis in situ havenot achieved convincing clinical acceptance or commercial success. Oneproblem identified by the present inventors is the substantialdifference in the modulus of elasticity between the vertebral bonyelements, including the vertebral end plates, and the annulus fibrosuson the one hand, and the implanted elements on the other. The highmodulus of elasticity of the implanted material is disadvantageous sinceit does not dampen impacts or sudden increases in intradiscal pressureduring extreme bending or torsion, especially during high loading peaks.The large difference in the modulus of elasticity between implanted discmaterials and adjacent tissues can also lead to softening of thevertebral end plates and adjacent bone (spongeosus), resulting insubsidence of the nuclear implant. Migration and expulsion of theimplant can also occur.

Therefore, there is a need for an improved nuclear implant.

SUMMARY

In accordance with another exemplary embodiment, a kit for implanting anucleus replacement device comprises a spinal implant device and aninflation stylus. The inner fillable enclosure has a proximal end with aproximal opening and a distal end with a distal opening. The outerfillable enclosure has a proximal end and a distal end, and the proximaland distal ends of the inner and outer fillable enclosures are coupledtogether so that the outer fillable enclosure encapsulates the innerfillable enclosure. A distal plug seals the distal opening in the distalend of the inner fillable enclosure and a proximal plug seals theproximal opening in the proximal end of the inner fillable enclosure.The proximal plug has a first lumen for providing access to the innerenclosure and a second lumen for providing access to the outerenclosure. The inflation stylus is adapted to mate with the proximalplug, and the inflation stylus comprises a first lumen for deliveringfluid to the inner enclosure and a second lumen for delivering fluid tothe outer enclosure.

In some embodiments, a reinforcing band surrounds a perimeter of theouter fillable enclosure. The reinforcing band may comprise a textile. Acontrol element may be coupled to a central zone of the annularreinforcement band. At least one pull string may be coupled to an edgeof the annular reinforcing band.

In some embodiments, a delivery sheath surrounds the inflation stylus,wherein the delivery sheath is movable from a delivery position to adeployed position. The control element and at least one pull string arepositioned between the delivery sheath and the inflation stylus.

According to an exemplary embodiment, a spinal implant device comprisesan inner fillable enclosure and an outer fillable enclosure. The innerfillable enclosure has a proximal end with a proximal opening and adistal end with a distal opening. The outer fillable enclosure has aproximal end and a distal end, and the proximal and distal ends of theinner and outer fillable enclosures are coupled together so that theouter fillable enclosure substantially encapsulates the inner fillableenclosure. A distal plug seals the distal opening in the distal end ofthe inner fillable enclosure and a proximal plug seals the proximalopening in the proximal end of the inner fillable enclosure. A proximalplug seals the proximal opening in the proximal end of the innerfillable enclosure. The proximal plug has a first lumen for providingaccess to the inner enclosure and a second lumen for providing access tothe outer enclosure. In some embodiments, the first lumen for providingaccess to the inner enclosure remains open after implantation.

In some embodiments, the inner and outer fillable enclosures comprises aunitary piece of material.

In some embodiments, the proximal plug is adapted to receive aninflation stylus comprising first and second lumens for delivering fluidto the inner and outer enclosures, respectively.

In some embodiments, a reinforcing band surrounds a perimeter of theouter fillable enclosure. The reinforcing band may comprise a textile. Acontrol element may be coupled to a central zone of the annularreinforcement band. At least one pull string may be coupled to an edgeof the annular reinforcing band.

In some embodiments, the outer enclosure is filled with a curablesilicone material.

In accordance with another exemplary embodiment, a method of implantinga prosthetic device into an intervertebral space having a nucleuspulposus surrounded by an annulus fibrosus comprises penetrating theannulus fibrosus; removing the nucleus pulposus to create a enucleateddisc cavity; inserting a fillable disc implant device into theenucleated disc cavity, the fillable disc implant device having an innerfillable enclosure forming an inner enclosure and an outer fillableenclosure coupled to the inner fillable enclosure so that the outerfillable enclosure substantially completely surrounds the inner fillableenclosure; inflating the inner fillable enclosure with a fluidic medium;inflating the outer fillable enclosure with a curable medium; allowingthe curable medium to cure; removing the fluidic medium from the innerfillable enclosure; and leaving the inner fillable enclosure vented sothat fluids may enter and exit the inner fillable enclosure.

In some embodiments, the fluidic medium comprises a substantiallyincompressible fluid, such as a contrast medium.

In some embodiments, a reinforcing band for reinforcing the perimeter ofthe fillable disc implant is provided. The reinforcing band is insertedinto the enucleated disc cavity and manipulated to create a pocket forreceiving the fillable disc implant. The reinforcing band may bemanipulated by pulling an inferior edge of the reinforcing band and asuperior edge of the reinforcing band to pull the edges toward theinterior of the enucleated disc cavity; and activating a control elementin a central portion of the reinforcing band to press the annularreinforcing band outward in the central portion toward the annulusfibrosus of the enucleated disc cavity. The inferior and superior edgesof the reinforcing band may be pulled by using inferior and superiorpull strings disposed at the inferior and superior edges of thereinforcing band. The control element may be activated by using aflexible ribbon to press the annular reinforcing band outward towardsthe annulus fibrosus. The pull strings and flexible ribbons may beremoved after the outer fillable enclosure is filled.

In accordance with yet another embodiment, a reinforcing band for aspinal disc implant comprises a textile band having a superior edge, aninferior edge, and a central zone between the superior and inferioredges. A superior drawstring is disposed at the superior edge of thetextile band for tightening the superior edge of the textile band whenpulled and an inferior drawstring disposed at the inferior edge of thetextile band for tightening the superior edge of the textile band whenpulled. A control element is disposed in the central zone for expandingthe central zone. The control element may comprise a metal ribbon.

The term “coupled” is defined as connected, although not necessarilydirectly. The terms “a” and “an” are defined as one or more unless thisdisclosure explicitly requires otherwise. The terms “substantially,”“approximately,” and “about” are defined as largely but not necessarilywholly what is specified (and includes what is specified; e.g.,substantially 90 degrees includes 90 degrees and substantially parallelincludes parallel), as understood by a person of ordinary skill in theart. In any disclosed embodiment, the terms “substantially,”“approximately,” and “about” may be substituted with “within [apercentage] of” what is specified, where the percentage includes 0.1, 1,5, and 10 percent.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a system,or a component of a system, that “comprises,” “has,” “includes” or“contains” one or more elements or features possesses those one or moreelements or features, but is not limited to possessing only thoseelements or features. Likewise, a method that “comprises,” “has,”“includes” or “contains” one or more steps possesses those one or moresteps, but is not limited to possessing only those one or more steps.Additionally, terms such as “first” and “second” are used only todifferentiate structures or features, and not to limit the differentstructures or features to a particular order.

A device, system, or component of either that is configured in a certainway is configured in at least that way, but it can also be configured inother ways than those specifically described.

Any embodiment of any of the systems and methods can consist of orconsist essentially of—rather than comprise/include/contain/have—any ofthe described elements, features, and/or steps. Thus, in any of theclaims, the term “consisting of” or “consisting essentially of” can besubstituted for any of the open-ended linking verbs recited above, inorder to change the scope of a given claim from what it would otherwisebe using the open-ended linking verb.

The feature or features of one embodiment may be applied to otherembodiments, even though not described or illustrated, unless expresslyprohibited by this disclosure or the nature of the embodiments.

Details associated with the embodiments described above and others arepresented below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a top plan view of an implant in accordance with an embodimentof the present disclosure;

FIG. 2 is a left plan view of the implant of FIG. 1;

FIG. 3 is a right plan view of the implant of FIG. 1;

FIG. 4 is a side plan view of the implant of FIG. 1;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

FIG. 6 is an enlarged view of a distal plug of the implant of FIG. 1;

FIG. 7 is an enlarged view of a proximal plug of the implant of FIG. 1;

FIG. 8 is a perspective view of an implant blank for forming the implantof FIG. 1;

FIG. 9 is a cut-away perspective view of the implant blank of FIG. 8after the implant blank has been partially inverted;

FIG. 10 is an inflation stylus inserted into the distal plug of theimplant of FIG. 1;

FIG. 11 is a plan view of the distal end of the inflation stylus of FIG.10;

FIG. 12 is a plan view of the proximal end of the inflation stylus ofFIG. 10;

FIG. 13 is a sectional view of the distal end of another inflationstylus;

FIG. 14 illustrates an annular reinforcing band for use with the implantof FIG. 1, with a deflated implant located in the interior of the band;

FIG. 15 illustrates the annular reinforcing band of FIG. 14, with afilled implant;

FIG. 16 illustrates the annular reinforcing band of FIG. 14 duringdeployment;

FIG. 17 is a sectional view of the textile band of FIG. 13;

FIG. 18 illustrates a first step in implanting the implant assembly ofFIG. 1;

FIG. 19 illustrates a second step in implanting the implant assembly ofFIG. 1;

FIG. 20 illustrates a third step in implanting the implant assembly ofFIG. 1;

FIG. 21 illustrates a fourth step in implanting the implant assembly ofFIG. 1;

FIG. 22 illustrates a fifth step in implanting the implant assembly ofFIG. 1; and

FIG. 23 illustrates a sixth step in implanting the implant assembly ofFIG. 1.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, in which are shown exemplary but non-limiting andnon-exhaustive embodiments of the invention. These embodiments aredescribed in sufficient detail to enable those having skill in the artto practice the invention, and it is understood that other embodimentsmay be used, and other changes may be made, without departing from thespirit or scope of the invention. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of theinvention is defined only by the appended claims. In the accompanyingdrawings, like reference numerals refer to like parts throughout thevarious figures unless otherwise specified.

Nuclear Implant

Referring to FIGS. 1-8, an embodiment of a minimally invasive orpercutaneously deliverable spinal implant 100 includes an outer fillableenclosure 102 and an inner fillable enclosure 104. Outer fillableenclosure 102 forms an outer enclosure 106, and inner fillable enclosure104 forms a inner chamber 108. Inner chamber 108 is encapsulated withinouter chamber 102. As used herein, encapsulated means that inner chamber108 is substantially contained within outer chamber 106 such that innerchamber 108 is substantially surrounded on all sides by outer chamber106. Outer and inner fillable enclosures 102, 104 may be formed as aseamless, unitary piece of an elastomeric material, such as siliconerubber. The use of an elastomeric material produces compliant outer andinner enclosures 102, 104. That is, the outer and inner enclosures 102,104 expand as the internal pressure increases when filled with a curablematerial. The use of compliant enclosures provides certain advantages.Compliant enclosures accommodate the irregular, flat or discoidconfiguration of the nuclear space. Furthermore, compliant enclosurescan help maintain an appropriate modulus of elasticity of the nuclearimplant following elastomeric curing, and help preserve bio-mechanicalmobility of the vertebral segment, and help allow unhindered deformationof the cured silicone component into the central void. The physicalcharacteristics of inner and outer fillable enclosures 102, 104 may betailored to provide desired physical outcomes. For example, in someembodiments, enclosures 102, 104 preferentially expand in a transverseplane. In some embodiments, inner and outer fillable enclosures 102, 104may be completely or partially semi-compliant or non-compliant (i.e.,the do not expand or minimally expand as the internal pressure isincreased). In some embodiments, different parts of inner and outerfillable enclosures 102, 104 may be formed of different materials toprovide different characteristics to enclosures 102, 104.

Implant 100 is preferably sized so that it can be insertedpercutaneously or using minimally invasive surgery into a enucleatedintervertebral disc cavity while deflated and then filled to fill theenucleated cavity. In one embodiment, the exterior of filled implant 100is approximately 30 mm in length, 20 mm in width, and 10 mm in height,and the exterior of inner fillable enclosure 104 is approximately 9 mmlong, 6 mm wide, and 6 mm thick. In some embodiments, the enclosure doesnot expand significantly when it is filled (i.e., it is non-compliant orsemi-compliant). In other embodiments, the implant is filled so that theimplant expands by approximately 100% (i.e., doubles in size) whenimplanted. In other embodiments, the implant is filled so that theimplant expands by more than 100% when implanted.

Outer fillable enclosure 102 has a first (or proximal) end 110 and asecond (or distal) end 112. Inner fillable enclosure 104 has a first (orproximal) end 114 coupled to a proximal neck 116. A second (or distal)end 118 of inner fillable enclosure 104 is coupled to a distal neck 120.An end portion 122 of distal neck portion 120 is coupled to distal end112 of outer fillable enclosure 102, and an end portion 124 of proximalneck 116 is coupled to proximal end 110 of outer fillable enclosure 102.In the illustrated embodiment, end portion 124 of proximal neck 124 iscoupled to proximal end 110 of outer fillable enclosure 102 by formingthem together as a unitary piece, as will be described in more detailbelow. Distal end 112 of outer fillable enclosure 102 is inverted andbonded to end portion 122 of distal neck portion to form a substantiallyfluid tight seal. Coupling the enclosures together in this manner formsa substantially fluid tight outer chamber 106.

A proximal plug 126 is located in the opening formed by proximal neck116. Proximal neck 116 may have features, such as grooves 148, formating with matching features on proximal plug 126 to assist in locatingproximal plug 126. Proximal plug 126 may be inserted into and bondedwith proximal neck 116. Proximal plug 126 is adapted to mate with aninflation tip 192 of an inflation stylus 130. A receptacle 132 receivesa first lumen 186 of inflation tip 192 to deliver material throughaperture 134 into outer chamber 106. Aperture 134 may be a bottleneck indelivering material to outer chamber 106, and may be formed as a skivedhole to maximum the size of aperture 134. Proximal plug 126 may be madeof silicone or another material which is compatible with enclosures 102,104, and may be manufactured using conventional manufacturingtechniques, such as injection molding.

In some embodiments, a locking feature to help prevent inadvertentdislodgment of inflation stylus 130 from proximal plug 126 is provided.For example, a recess 136 may be provided in proximal plug 126 and amating feature (e.g., bead 152, FIG. 13) may be provided on inflationtip 192.

An access lumen 138 extends through proximal plug 126 to provide accessto interior chamber 108. As can be seen in FIG. 3, receptacle 132 andaccess lumen 138 can be arranged to prevent improper installation ofinflation stylus 130. In some embodiments (such as shown in FIG. 10), akey 214 is provided to physically prevent improper installation ofinflation stylus 130. Key 214 may be used to control the depth ofinsertion of inflation tip 130. Alternatively, in other embodiments,positioning collar 190 may be used to control the depth of insertion ofinflation tip 130. Access lumen 138 is configured to remain open afterimplantation to serve as a vent for internal chamber 108.

A distal plug 140 is disposed in distal neck 120 to seal the distalneck. Distal plug 140 may have a cylindrical recess 142 on the interiorside for receiving a distal end 200 of a contrast lumen 188 of inflationstylus 130. Another cylindrical recess 146 may be provided on distalplug 140. Distal plug 140 may be made of silicone or another materialwhich is compatible with enclosures 102, 104, and may be manufacturedusing conventional manufacturing techniques, such as injection molding.

Textile Band

Referring to FIGS. 14-17, an optional annular reinforcing band 160 maybe provided to reinforce implant 100. Annular reinforcing band 160 isuseful when a patient's annulus fibrosus is damaged. In one embodiment,annular reinforcing band 160 comprises a tubular, woven textilematerial. Annular reinforcing band 160 is disposed around the perimeterof the lateral edges of implant 100 to minimize or prevent overinflation of the outer and inner balloons 102, 104 circumferentially.Controlling circumferential expansion also encourages vertical expansionof balloons 102, 104 to distract the adjacent vertebra and widen thedisc space. The vertebral superior and inferior end plates constrain thevertical expansion of the implant 100. In some embodiments, annularreinforcing band 160 is formed of a woven material. In one embodiment,annular reinforcing band 160 uses an axial weave which minimizes orsubstantially prevents shortening of the band when it is expanded. U.S.Pat. No. 8,636,803, entitled Percutaneous Implantable Nuclear Implant,discloses other suitable constructions of annular reinforcing band 160,and is hereby incorporated by reference in its entirety for allpurposes. One suitable material for annular reinforcing brand 160 isultra-high molecular weight polyethylene fiber, such as DYNEEMA® fiberavailable from Koninklijke DSM N.V., Heerleen, the Netherlands.

Annular reinforcement band 160 has a superior edge 162, an inferior edge164, and a central zone 166 between superior and inferior edges 162,164. One or more pull strings and control elements are provided to helpplace annular reinforcement band during deployment of implant 100. Inone embodiment, an inferior pull string 168, a superior pull string 170,and a control element 172 are provided. Superior pull string is placedin a pocket 176 or otherwise coupled to superior edge 162 of annularreinforcement band 160. Similarly, inferior pull string 168 is placed ina pocket 176 or otherwise coupled to inferior edge 164 of annularreinforcement band 160. Inferior and superior pull strings can be usedas a drawstring (i.e., pulled) during deployment to pull the edges ofannular reinforcement band 160 inward, thereby helping to constrain andposition implant 100. Control element 172 is disposed in central zone166 of annular band 160. If annular band 160 comprises a tubularmaterial, then control element 172 is placed inside the tubularmaterial. In other embodiments, control element 172 is placed in apocket formed on annular reinforcing band 160. Control element 172 maybe a wire, such as a flat ribbon of nitinol, which runs around theperimeter of annular reinforcement band 160. Control element 172 may beused to press annular reinforcement band 160 outward to an annulusfibrosus. Further details of the operation of control element 172 andpull strings 168, 170 will be discussed below.

Inflation Stylus and Delivery Sheath

Referring to FIGS. 10-13, inflation stylus 130 may be used inconjunction with a delivery sheath to deliver implant 100 and annularreinforcement band 160. Inflation stylus 130 comprises a shaft 180 witha proximal end 182 and a distal end 184. A first lumen 186 and a secondlumen 188 extend through shaft 180. A positioning collar 190 is providedto maintain first and second lumen 186, 188 in a desired potion. Thedistal ends of first and second lumens 186, 188 form an inflation tip192 which is configured to mate with proximal plug 126.

First (or silicone) lumen 186 extends from proximal end 182 of inflationstylus 130 to distal end 184 of inflation stylus 130. When inflationstylus 130 is mated with proximal plug 126, an aperture 194 at thedistal end of first lumen 186 is coincident with aperture 134 ofproximal plug 126 to allow fluid communication between outer chamber 106and first lumen 186. Proximal end of lumen 186 is provided with aconnector 196 for connection to common inflation tools (such assyringes) known to those of skill in the art.

In certain embodiments, such as that illustrated in FIG. 13, a vent 198may be provided to allow air to exit silicone lumen 186 when silicone oranother suitable material is delivered to outer chamber 106. Vent 198may be large enough to allow air to freely move through it, whileresisting more viscous fluids such as curable silicone. It should beunderstood that as used herein, “silicone lumen” means a lumen fordelivery of any desired fluid to outer chamber 106, and can encompassmaterials other than silicone. Vent 198 preferably extends through shaft180 to vent to atmosphere at the proximal end of inflation stylus 130.

Second (or contrast) lumen 188 extends from proximal end 182 ofinflation stylus 130 to distal end 184 of inflation stylus 130. Contrastlumen 188 extends out the proximal end of inflation stylus 130.Preferably, contrast lumen 188 is independently movable with respect toinflation stylus 130 so that the position of the distal end 200 ofcontrast lumen 188 may be extended and withdrawn with respect to thedistal end 184 of inflation stylus 130. For delivery prior toimplantation, contrast lumen 188 can extend through access lumen 138 andthe distal tip of contrast lumen 188 can be positioned within recess 142of distal plug 140 to hold it into place. Contrast lumen 188 can be usedto both deliver and remove fluids from inner chamber 108. In someembodiments, distal end 200 of contrast lumen 188 is preformed into ashape which allows easier removal of fluid from inner chamber 108. Inone specific embodiment, contrast lumen 188 is preformed into a curvedshape which allows easier access to the bottom of inner chamber 108. Thecurved shape combined with the ability to extend and withdraw contrastlumen 188 allows it to be adjusted when used to withdraw fluid frominner chamber 108. It should be understood that as used herein,“contrast lumen” should be understood to mean a lumen for delivery ofany desired fluid to inner chamber 108, and can encompass materialsother than contrast medium. Contrast medium may be used to ensurevisibility under imaging, such as fluoroscopy.

Referring to FIG. 16, a delivery sheath 174 comprises a lumen sized tofit over shaft 180 of inflation stylus 130. To deliver implant 100,implant 100 is placed onto inflation tip 192, and the assembled bodiesare withdrawn into the distal end of delivery sheath 174. If pull wires168, 170 and control element 172 are used, they may be placed throughthe lumen of the delivery sheath.

Method of Manufacturing an Implant

Referring to FIGS. 8-9, implant 100 may be formed by forming an implantblank 150, which comprises outer fillable enclosure 102 coupled to innerfillable enclosure 104. Implant blank 150 may be manufactured usingconventional manufacturing techniques, such as injection molding or dipmolding. After implant blank 150 is formed, implant blank 150 ispartially inverted to place inner fillable enclosure 104 into theinterior of outer fillable enclosure 102. Distal plug 140 is insertedinto distal neck 120, and proximal plug 126 is inserted into proximalneck 116. Additional details regarding one suitable manufacturingtechnique are disclosed in co-pending application 62/074,295, entitled“Percutaneous Implantable Nuclear Prosthesis,” which was filed on Nov.4, 2014 and is hereby incorporated by reference in its entirety.

Method of Deploying an Implant

Referring to FIGS. 18-23, fillable implant 100 is particularly wellsuited for deployment using minimally invasive or percutaneous surgicaltechniques.

To implant fillable implant 100, the existing nucleus pulposus isremoved by performing a discectomy while leaving annulus fibrosus 202substantially intact. Preferably, the discectomy is performed usingminimally invasive surgical techniques, such as percutaneous techniques,which uses a cannula 208 to access the disc cavity 206 through a smallopening in annulus fibrosus 202. In one embodiment, the disc cavity isaccessed using a posterolateral approach through Kambin's triangle. Ananterior approach may also be used. To preserve the integrity of theannulus fibrosus as much as possible, the annulotomy in the annulusfibrosus may be created by penetrating the fibrosus annulus with a guidepin (e.g., a K-wire) and a series of increasing diameter dilators placedover the guide pin. Once the desired diameter is obtained, the accesscannula 208 is placed over the largest diameter, and the dilator set isremoved. This procedure spreads the fibrous bands of the annulusfibrosus to create an annulotomy without excising (i.e., removing) anytissue, which aids in the healing process. Alternatively, the fibrosusmay be stabbed with a scalpel to create vertical slit to gain access tothe nucleus space.

Once cannula 208 is in place, the physician may remove the existing discusing any suitable instruments (such as rongeurs). The physician shouldavoid violating the circumferential annulus or penetrating the superiorand inferior vertebral end plates. The physician may monitor theprogress of the discectomy by inserting a compliant imaging balloon intothe disc space and inflating the imaging balloon with a contrast agent.In some embodiments the imaging balloon comprises a modified implantcomprising outer inflatable enclosure 102 without an inner inflatableenclosure. The imaging balloon also serves as a trial implant to predictthe volume, shape and placement of the final implant.

Once the existing nucleus pulposus has been removed to the satisfactionof the physician, annulus fibrosus 202 and vertebral end plates 204 forma substantially empty enucleated disc cavity 206 (FIG. 18).

The implant 100, which is loaded into a delivery sheath 174, is placedinto enucleated disc cavity 206 through cannula 208. Typically, theimplant will be delivered to the far end of the disc cavity. Thedelivery sheath 174 is then withdrawn to expose the implant 100 insidethe enucleated disc cavity.

If the optional annular reinforcing band is provided, control member 172is manipulated to press central zone 166 of annular reinforcing band 160substantially flush against the inner surface of annulus fibrosus 202.Pull strings 168, 170 may be pulled to tighten edges 162, 164 of annularreinforcing band 160 and form a pocket for receiving implant 100.Control member 172 and pull strings 168, 170 may include radiopaquefeatures (such as platinum or nitinol coating) to aid in visualizationunder fluoroscopy.

In some embodiments, inner chamber 108 is first filled with a fluid to adesired size. In one specific embodiment, a substantially incompressiblefluid 210 is used, such as a contrast medium. Prior to inflating theinner chamber, air should be purged from the system using, for example,a vacuum locking syringe. Fluid 210 is delivered using contrast lumen188 of inflation stylus 130. The inflation pressure of the inner chamber108 is selected to fill inner fillable enclosure 104 to a desired size.

Inflation stylus 130 is used to deliver a curable material 212 to outerchamber 106. Curable material 212 is preferably an elastomeric material,such as silicone rubber containing a radiopaque material (such as bariumsulfate). It is not necessary to evacuate air from the outer chamberprior to inflation because of the included vent. Curable material 212may be chosen so that it polymerizes with the material of inner andouter fillable enclosures 102, 104 to form a unitary member. The modulusof elasticity and other characteristics of curable material 212 can beselected based upon patient specific parameters. For instance, younger,more active patients may require a firmer material than less mobilegeriatric patients. Once outer chamber 106 is filled to a desiredpressure, curable material 212 is allowed to cure. In some embodiments,the curable material comprises curable silicone which cures in a shortperiod of time, for example, less than 10 minutes, or less than 5minutes. The use of shorter curing periods may help prevent thedissolution of solvent from the curable medium to the fillableenclosures which may occur with longer curing mediums. Such leaching ofsolvents may adversely affect the structural integrity of the fillableenclosures.

After curable material 212 is allowed to cure, substantiallyincompressible fluid 210 is removed using contrast lumen 188. Asdiscussed earlier, contrast lumen 188 may be moved and manipulated toremove as much incompressible fluid 210 as is desired. Preferably,substantially all of fluid 210 is removed; however, some fluid is likelyto remain and it is not necessary to remove all fluid.

Once fluid 210 has been removed and curable material 212 is sufficientlycured, inflation stylus 130 can all be withdrawn through cannula 208,and cannula 208 can be removed. If the optional annular reinforcing bandis used, pull strings 168, 170, control member 172 are also withdrawnthrough cannula 208.

Thus, the implant 100 comprises an annular ring of cured material 212surrounding hollow interior chamber 108. Interior chamber 108 remainsopen to allow fluids to enter and exit, thereby functioning as a shockabsorber. This structure allows for vertical and horizontal loadstresses placed on the intervertebral disc space to be redirectedinward, centrally toward interior chamber 108 (see direction arrows ofFIG. 23) instead of outward. Moreover, annular reinforcing band 160encourages tissue in-growth of native annulus fibrosus 202, therebyproviding reinforcement to native annulus fibrosus 202.

The above specification and examples provide a complete description ofthe structure and use of exemplary embodiments. Although certainembodiments have been described above with a certain degree ofparticularity, or with reference to one or more individual embodiments,those skilled in the art could make numerous alterations to thedisclosed embodiments without departing from the scope of thisinvention. As such, the various illustrative embodiments of the presentdevices are not intended to be limited to the particular formsdisclosed. Rather, they include all modifications and alternativesfalling within the scope of the claims, and embodiments other than theone shown may include some or all of the features of the depictedembodiment. For example, components may be combined as a unitarystructure, and/or connections may be substituted (e.g., threads may besubstituted with press-fittings or welds). Further, where appropriate,aspects of any of the examples described above may be combined withaspects of any of the other examples described to form further exampleshaving comparable or different properties and addressing the same ordifferent problems. Similarly, it will be understood that the benefitsand advantages described above may relate to one embodiment or mayrelate to several embodiments.

The claims are not intended to include, and should not be interpreted toinclude, means-plus- or step-plus-function limitations, unless such alimitation is explicitly recited in a given claim using the phrase(s)“means for” or “step for,” respectively.

1. A kit for implanting a nucleus replacement device, comprising: aspinal implant device comprising: an inner fillable enclosure having aproximal end with a proximal opening and a distal end with a distalopening; an outer fillable enclosure having a proximal end and a distalend, wherein the proximal ends of the inner and outer fillableenclosures are coupled together and the distal ends of the inner andouter fillable are coupled together so that the outer fillable enclosureencapsulates the inner fillable enclosure; a distal plug for sealing thedistal opening in the distal end of the inner fillable enclosure; and aproximal plug for sealing the proximal opening in the proximal end ofthe inner fillable enclosure, the proximal plug having an access lumenfor providing access to the inner fillable enclosure and a receptaclewith an aperture for providing access to the outer fillable enclosure,wherein the access lumen for providing access to the inner fillableenclosure is configured to remain open after implantation; and aninflation stylus adapted to mate with the proximal plug, wherein theinflation stylus comprises: an adjustable first lumen for movablyextending through the access lumen to deliver and remove fluid from theinner enclosure; and a second lumen for delivering fluid to the outerenclosure.
 2. The kit of claim 1, further comprising a reinforcing bandsurrounding a perimeter of the outer fillable enclosure.
 3. The kit ofclaim 2, wherein the reinforcing band comprises a textile.
 4. The kit ofclaim 2, further comprising a control element coupled to the annularreinforcement band.
 5. The kit of claim 4, further comprising at leastone pull string coupled to an edge of the annular reinforcing band. 6.The kit of claim 5, wherein the at least one pull string is sewn into achannel in the reinforcing band.
 7. The kit of claim 5, furthercomprising a delivery sheath surrounding the inflation stylus, whereinthe delivery sheath is movable from a delivery position to a deployedposition.
 8. The kit of claim 7, wherein the control element and atleast one pull string are positioned between the delivery sheath and theinflation stylus.
 9. The kit of claim 1, further comprising a curablesilicone material for injection into the outer fillable enclosure. 10.The kit of claim 9, wherein the curable silicone material substantiallycures within five minutes.
 11. A spinal implant device comprising: aninner fillable enclosure having a proximal end with a proximal openingand a distal end with a distal opening; an outer fillable enclosurehaving a proximal end and a distal end, wherein the proximal ends of theinner and outer fillable enclosures are coupled together and the distalends of the inner and outer fillable are coupled together so that theouter fillable enclosure substantially encapsulates the inner fillableenclosure; a distal plug for sealing the distal opening in the distalend of the inner fillable enclosure; and a proximal plug for sealing theproximal opening in the proximal end of the inner fillable enclosure,the proximal plug having an access lumen for providing access to theinner fillable enclosure and a receptacle with an aperture for providingaccess to the outer fillable enclosure, wherein the access lumen forproviding access to the inner fillable enclosure is configured to remainopen after implantation.
 12. The spinal implant device of claim 11,wherein the inner and outer fillable enclosures comprise a unitary pieceof material.
 13. The spinal implant device of claim 11, wherein theproximal plug is adapted to receive an inflation stylus comprising firstand second lumens for delivering fluid to the inner and outerenclosures, respectively.
 14. The spinal implant device of claim 11,further comprising a reinforcing band surrounding a perimeter of theouter fillable enclosure.
 15. The spinal implant device of claim 14,wherein the reinforcing band comprises a textile.
 16. The spinal implantdevice of claim 14, further comprising a removable control elementcoupled to the reinforcement band in a central zone of the reinforcingband.
 17. The spinal implant device of claim 14, further comprising atleast one removable pull string coupled to an edge of the annularreinforcing band.
 18. The spinal implant device of claim 11, wherein theouter enclosure is filled with a curable silicone material.
 19. Thespinal implant device of claim 11, further comprising a retainingelement for retaining the device on an inflation stylus.
 20. A method ofimplanting a prosthetic device into an intervertebral space having anucleus pulposus surrounded by an annulus fibrosus comprising:penetrating the annulus fibrosus to create an annulotomy; removing thenucleus pulposus to create a enucleated disc cavity through theannulotomy; inserting an fillable disc implant device into theenucleated disc cavity, the fillable disc implant device having an innerfillable enclosure and an outer fillable enclosure coupled to the innerfillable enclosure so that the outer fillable enclosure substantiallycompletely encapsulates the inner fillable enclosure; inflating theinner fillable enclosure with a fluidic medium; inflating the outerfillable enclosure with a curable medium; allowing the curable medium tocure; removing the fluidic medium from the inner fillable enclosure; andleaving the inner fillable enclosure vented so that fluids may enter andexit the inner fillable enclosure.
 21. The method of claim 20, whereinthe fluidic medium comprises a substantially incompressible fluid. 22.The method of claim 21, wherein the substantially incompressible fluidcomprises a contrast medium.
 23. The method of claim 20, furthercomprising: providing a reinforcing band for reinforcing the perimeterof the fillable disc implant; inserting the reinforcing band into theenucleated disc cavity; and manipulating the reinforcing band to createa pocket for receiving the fillable disc implant;
 24. The method ofclaim 23, wherein the step of manipulating the reinforcing bandcomprises: pulling an inferior edge of the reinforcing band and asuperior edge of the reinforcing band to pull the edges toward theinterior of the enucleated disc cavity; and activating a control elementin a central portion of the reinforcing band to press the annularreinforcing band outward in the central portion toward the annulusfibrosus of the enucleated disc cavity.
 25. The method of claim 24,wherein the step of pulling the inferior and superior edges of thereinforcing band comprises pulling inferior and superior pull stringsdisposed at the inferior and superior edges, respectively, of thereinforcing band; and
 26. The method of claim 24, wherein the step ofactivating a control element comprises using a flexible ribbon to pressthe annular reinforcing band outward towards the annulus fibrosus. 27.The method of claim 20, further comprising: removing the pull stringsand flexible ribbons after the outer fillable enclosure is filled.
 28. Areinforcing band for a spinal disc implant, comprising: a textile bandhaving a superior edge, an inferior edge, and a central zone between thesuperior and inferior edges; a superior drawstring disposed at thesuperior edge of the textile band for tightening the superior edge ofthe textile band when pulled; an inferior drawstring disposed at theinferior edge of the textile band for tightening the superior edge ofthe textile band when pulled; and a control element disposed in thecentral zone for expanding the central zone.
 29. The band of claim 28,wherein the control element comprises a metal ribbon.
 30. The band ofclaim 29, wherein the metal ribbon comprises nitinol.
 31. The band ofclaim 30, further comprising radiopaque features on the control element.